Having lost their nesting tree holes to more aggressive European Starlings and House Sparrows, these gorgeous birds were decreasing in population. But thanks to bluebird fans who have built millions of special nest boxes, the sweet "chirrup" of these melodic songbirds once again fills the spring air.

Look For: The male is sky-blue above with an orange breast and throat, and a white belly. Female is duller.

Length: 6-7 1/2".

Habitat: Grasslands, open forests, yards, farms.

Range: Southeastern Canada and eastern U.S. (found to the north mainly in summer).